This document outlines basic safety warnings for septic systems and cesspools, and provides some safety suggestions for septic system inspectors, septic system inspections, septic pumping contractors, and home owners.
The septic hazard news video at right recounts a child falling into a septic tank and a separate septic fall-in fatality.
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Providing inspection and diagnosis of on-site waste disposal systems is an extremely valuable public service
which helps protect people from expensive unanticipated septic system repair costs and helps protect public health
by assuring sanitary disposal of sewage and gray water waste from buildings.
More importantly though, septic system
inspections may detect and warn about serious safety hazards at some properties. The strong warnings issued below
intend to reduce septic system safety hazards for inspectors and property owners/occupants, but it is not the author's
intention to dissuade inspectors from providing this valuable service. But danger lurks at cesspools, open covers, tanks or tank covers in poor condition,
and from high levels of methane gas CH4 or hydrogen sulfide H2S.
These septic system dangers include the risk of collapse, falling, asphyxiation, explosion, and other potentially fatal hazards as well as risks of unsanitary conditions such as bacterial or viral infections.
There can be other unexpected hazards when inspecting building sites and septic systems. In the photo series above, the author was inspecting the home shown from outside before looking in the crawl space to locate the main waste line exit point and thus
before predicting the probable location of the septic tank. Walking close to this house should have set off
an alarm about possible unsafe conditions: poor maintenance, old home, of an age likely to have used a
steel septic tank. In fact the author found the tank very quickly by stepping through its cover, avoiding serious
injury or even possible fatality mostly by luck. It was throw myself sideways into the briars and garbage at the
site or fall completely into the septic tank.
A Safety Guide for Septic System Inspection, Cleaning, Pumping, and Homeowner Care
Don't work alone: Falling into a septic tank or even leaning over a septic tank can be fatal.
Do not work on or at septic tanks alone - workers can become suddenly overcome by methane gas.
Do not ever enter a septic tank unless you are specially trained and are wearing the special equipment and gear for that purpose, including self-contained breathing apparatus.
Do not go into a septic tank to retrieve someone who has fallen in and was overcome by toxic gases unless you are equipped with a self-contained breathing apparatus (SCBA). If a SCBA is not available, call for emergency services and put one or more fans at the top of the septic tank to blow in fresh air.
Don't lean over a septic tank opening: Do not lean over or stick your head into the septic tank to examine its interior - you could fall in to the
tank or become overcome by gases and fall into the tank, an event which is likely to be fatal.
Don't ignite flames Do not light a flame at or near the tank - methane gas is explosive. At one tank pump out my client described
the explosion and burns received by the pumping contractor when he stood by the tank and lit a cigarette. A reader reported a stunning methane gas explosion that
damaged nearby buildings when a brush fire was built over a septic tank. [There are safer ways to find the septic tank.]
Site must be ventilated: Decomposing wastes in the septic tank produce toxic or otherwise dangerous gases (such as methane which is both explosive
and in a septic tank methane gas is an asphyxiant) which can kill a human in a matter of minutes. When working on a tank be sure the area is well ventilated.
Rope off & Mark Dangerous Sites: If your inspection discover that there are dangerous conditions, such as an unsafe tank cover, tank collapse, or a home-made septic tank or cesspool (which are at increased risk of sudden collapse) such areas should be roped off and clearly marked as dangerous to prevent access until proper evaluation and repairs can be made.
Safe covers: be sure that the tank and its access ports have sound and secure covers that do not risk collapse and which cannot be removed by children.
Septic & Cesspool Collapse Hazards: Old steel tanks, thin, rusting steel or rotting home-made wood tank covers, site-built tanks and cesspools, and recently-pumped cesspools are at particular risk of
collapse. Falling into a septic tank or cesspool is likely to lead to rapid asphyxiation from methane and in cases of collapse, there is risk of becoming buried. The author has consulted in cases involving
such fatalities (homeowner fell into a site-built cesspool), and at one site inspection, walking near an overgrown area the author himself stepped through a rusting steel septic tank top, surviving only
by throwing himself into a nearby clump of brambles! Beware of the following additional septic system inspection hazards:
Bad septic tank covers: flimsy, rusted, old-steel, home-made, or missing septic tank/drywell/cesspool covers
Abandoned septic tanks: systems which may not have been filled-in
Collapsed, or collapsing septic tanks or cesspools
Additional unexpected septic components: possible presence of multiple components at a property, abandoned or in-use
Un-stable soils: Cesspools and septic systems in areas of unstable soils or areas of commonly-found site-built systems - collapse risk
Cesspool pumping or agitating: pumping, aerating, or agitating cesspools in an attempt to restore function can lead to sudden collapse of these systems, especially if the cesspool or septic tank was "site built" using stacked concrete blocks or stone
Shock & Electrical Hazards: when digging outdoors, watch out that you don't dig into and cut an electrical wire (or other buried
mechanical line such as a gas or water line). Buried electrical wires can look a lot like tree roots. Chopping through an electrical wire while digging to
find a septic system can be dangerous. [Thanks to Donica Ben for reminding us of this septic safety problem.]
Unsanitary conditions: Be alert for unsanitary conditions such as surface effluent or sewage backups into buildings, events which risk serious viral and bacterial hazards and which indoors, may require professional cleaning. Be alert for personal sanitation hazards when working around septic systems, such as open cuts or failure to wash properly after working on systems.
Damage to Septic Components: Avoid damaging septic system components or the building: Improper septic testing procedures, such as flooding a dosing-system,
can damage the system. Also, remember to check for leaks into or under the building being tested when running water into the building fixtures and drains. Don't leave water running unattended - at risk of flooding the building.
Methane Gas Hazards around Septic Systems, Methane Gas Toxicity vs. Methane Explosion & Asphyxiation Risks, How to Measure Methane Gas Levels
Methane Gas Hazards are primarily of explosion or asphyxiation - see SEPTIC METHANE GAS for details.
We commented above at Septic System Safety that methane gas which maybe encountered in septic system is both explosive
and an asphyxiant.
A thoughtful reader, George Fielder, previously a salesperson for GfG Instrumentation, pointed out that these are the hazards. (We had inaccurately stated that methane gas was "toxic".)
Readers who need more details about the safety concerns regarding methane gas in and around septic systems should be sure to review the septic system methane gas hazards and measurement and references
cited at SEPTIC METHANE GAS (also see Septic Methane Gas links at page left in this article)
Guide to Proper Abandonment of Un-used Septic Tanks
It is important to properly abandon un-used septic tanks, cesspools, or drywells. If an old septic tank, cesspool, or drywell is simply "left alone" there may be very serious cave-in or fall-in safety hazards.
In addition to having been consulted in fatalities involving humans, we have learned that falling into septic tanks and cesspools is a risk for animals as well. In 2008 Mark Cramer shared a report from an owner that that their horse fell into a septic tank and died tragically before it could be rescued. The collapsing septic tank was not in the location which the owners thought it would be found, and clearly it had an unsafe cover.
Properly abandoning a septic tank, drywell, or cesspool which is no longer in use involves at least the following steps:
Locate all of the un-used septic tanks, cesspools, drywells on the property. At some properties there may be multiple systems and tanks, such as a chain of old cesspools or one or more septic tanks with a separate drywell. See these articles on finding hidden, lost, buried septic system components:
HOW TO FIND A SEPTIC TANK which offers detailed steps and multiple approaches, including our septic tank and drainfield location videos. An experienced plumber or septic contractor can assist in these steps and may have special equipment that speeds the process. These subtopics are addressed
Pump out the septic tank, cesspool, or drywell - a septic pumping contractor performs this step.
Break open the tank bottom - so that it won't hold surface runoff, forming an un-wanted water or mud reservoir. If the septic tank is steel, often the contractor will dig out the tank, crush it, and then bury it back in the original hole. When we installed a new concrete septic tank the contractor buried the crushed steel one on edge alongside the new concrete tank.
Fill in the septic tank, cesspool, or drywell, or hole where the tank was located (if you crushed an old steel tank) with stone, rubble, and soil so that there is on future collapse hazard.
Document the location of the filled-in items so that future site work or building plans can avoid or at least anticipate these buried obstructions.
If newer septic tanks, cesspools, or drywells remain in use at the property, be sure that their locations are documented (see DOCUMENT TANK LOCATION ) and that each of these has an intact, secure cover that will not cave in nor be easily opened by a child (see SEPTIC TANK COVERS ) We've written elsewhere about the importance of keeping livestock off of septic drainfields and septic tanks. There may be an extra risk of livestock-caused septic tank collapse where old septic tank or cesspool covers or even new fiberglass septic tanks and covers are installed.
Don't Flush these things into a septic system: a list of what's ok and what's not ok to put into septic tanks and building drains
Septic Tank Location - How to Find the Septic Tank, how deep will the cover be, how to document its location - these methods also apply to locating a cesspool or drywell at a property.
Dye Tests: how to perform a Septic Loading and Dye Test - septic dye testing procedures in complete detail, a septic function test - a chapter in the above book.
Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
Technical Reviewers
Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to
the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.
Alan Carson Carson Dunlop Associates, Toronto, Ontario. Mr. Carson is a home inspection professional, educator, researcher, writer, and a principal of Carson Dunlop Associates, a Toronto home inspection and education firm. Mr. Carson is a past president of ASHI, the American Society of Home Inspectors
Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. (727) 595-4211 mark@BestTampaInspector.com 11/06 and 04/2008
Hankey and Brown home inspectors, Eden Prairie, MN, technical review by Roger Hankey, prior chairman, Standards Committee, American Society of Home Inspectors - ASHI. 952 829-0044 - hankeyandbrown.com 11/06
Arlene Puentes, a licensed home inspector, educator, and building failures researcher in Kingston, NY. 11/29/06
John Francis, Bioworks, Inc., marketing and technical services - editing/proof reading 4/07. "BioWorks provides environmentally responsible, safe and cost-effective solutions to the agriculture industry"
Thanks to Denise Cermola for permission to use the photo above, showing a dump truck collapsed into a seepage pit. (email 11/16/06 to 12/10/06). The contractor drove over this seepage pit connected to septic tank and caused total destruction of the system.
Thanks to George Fielder who points out that methane gas is not toxic, but rather (we add) the hazards of methane gas produced by septic systems include possible explosions or the asphyxiation of someone who enters or even just leans over a septic tank opening. (email 10/20/2007)
Thanks to Donica Ben who points out the danger of digging into buried electrical wires (11/11/07)
Technical reviewers are invited to comment or ask questions - contact us
Septic Tank Capacity vs Usage in Daily Gallons of Wastewater Flow, calculating required septic tank size, calculating septic tank volume from size measurements
Pennsylvania State Fact Sheets relating to domestic wastewater treatment systems include
Pennsylvania State Wastewater Treatment Fact Sheet SW-161, Septic System Failure: Diagnosis and Treatment
Pennsylvania State Wastewater Treatment Fact Sheet SW-162, The Soil Media and the Percolation Test
Pennsylvania State Wastewater Treatment Fact Sheet SW-l64, Mound Systems for Wastewater Treatment
Pennsylvania State Wastewater Treatment Fact Sheet SW-165, Septic Tank-Soil Absorption Systems
Document Sources used for this web page include but are not limited to: Agricultural Fact Sheet #SW-161 "Septic Tank Pumping," by Paul D. Robillard and
Kelli S. Martin. Penn State College of Agriculture - Cooperative Extension, edited and annotated by
Dan Friedman (Thanks: to Bob Mackey for proofreading the original source material.)
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